The Complete Joy of Home Brewing by Charlie Papazian is a classic. It's a fun, enthusiastic read. Some of the information is a bit dated, but it is an easy read.
If you kind of know the basics, Radical Brewing by Randy Mosher is also a fun read. I've tried a couple of the interesting and unsual things, and they haven't always worked as he describes, so I'm not sure he has tested all the things he suggests. Still, it contains lots of interesting history and perspective.
If you're in to Belgian beer at all, Brew Like a Monk and Farmhouse Ales are both excellent books with lots of good context and history as well as good technical information.
I'm currently half way through Gordon Strong's Brewing Better Beer. It's good, but I'd wait till you've done a few AG brews before getting too far in to it.
I have not read any of Jamil Zainasheff's books, so I'll leave it to others to recommend them.
T.